Evolution of biodegradation of deinking by-products used as alternative cover material
Ait-Benichou, Samah; Cabral, Alexandre
Abstract: Deinking by-products (DBP) have been used as alternative material for the construction of cover systems for municipal waste disposal facilities and acid-producing mine residues. Considering the high organic content of this material, biodegradation occurs as meteoric water infiltrates through the cover. This ultimately may result in changes with time of the properties of DBP, thus of its behaviour as percolation control layer. This study concerns the evolution of the biodegradation of DBP in laboratory tests performed at 38°C for 1460 days. Periods of intermittent water percolation allowed for collection of leachate, whereas gas samples were collected throughout the tests. The evolution of gas and leachate production was monitored in terms of quality and quantity. The results show that biodegradation did not significantly alter the compaction behavior of DBP. There is, however, a marked increase in void ratio and water content, and a slight increase in the relative density. It is significant to note that while the void ratio of the samples increased, the volume of the samples decreased, which means that the porous structure of the non-confined samples was no longer the same after 1460 d of accelerated biodegradation. The results of permeability tests performed at various confining stresses show that the hydraulic conductivity of compacted biodegraded DBP decreases from 7 to approximately 2 x 10-7 cm/s in 1460 days.
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